1. Field of the Invention
The present invention relates generally to vehicle suspension systems, and more specifically to a connector installed between a longitudinal leaf spring suspension and the associated axle of the vehicle. The present connector includes a pivot axis normal to the elongate axis of the axle and generally parallel to the elongate axis of the spring, permitting the axle to move angularly and laterally without imposing torsional forces on the leaf spring, thereby eliminating lateral binding of the spring and corresponding reduction in spring rate and travel.
2. Description of the Related Art
While most motor vehicles are adapted for travel over relatively smooth surfaces with only occasional travel over speed bumps, driveway ramps, etc., a relatively large class of vehicles is adapted for travel over relatively rough and unimproved surfaces. Such vehicles are usually constructed as light trucks or sport utility vehicles, and generally have relatively large suspension travel in order to provide for use over rough and unimproved surfaces. While such vehicles have found favor among the general public for recreational purposes, they are also widely used by construction firms, the military, and other users as well.
The two most important considerations in the suspension action of such vehicles are total travel, i. e., the amount of movement from full compression (xe2x80x9cbumpxe2x80x9d) to full extension (xe2x80x9cdroopxe2x80x9d), and articulation, i. e., the difference in travel extremes between diagonally opposite wheels or wheel assemblies at diagonally opposite corners of the vehicle. These characteristics are of critical importance in extreme terrain conditions, as obviously a wheel and tire which is not in contact with the underlying surface, is incapable of providing any tractive force (acceleration, braking, and/or steering) to propel and control the vehicle.
As a result, manufacturers and aftermarket suppliers alike have attempted to develop various solutions for these travel and articulation problems. It will be noted that as suspension travel is increased in any given vehicle, the problem of providing sufficient articulation becomes more critical. Greater suspension travel results in greater angularity in drive lines and axles relative to one another and to the vehicle chassis, creating an even greater problem in avoiding binding somewhere in the system.
This is particularly true in vehicles with solid axle systems, where the suspension elements (springs and shock absorbers) are connected between an axle which extends across the vehicle and the vehicle chassis or frame. While many vehicles adapted for rough terrain usage have independent suspensions with coil springs, a large number of such vehicles (particularly older vehicles) have solid axles (perhaps front and back) suspended by leaf springs, as this system has proven to be extremely durable and reliable.
However, such solid or straight axle drive and suspension systems are difficult to provide with sufficient articulation to correspond with the relatively large wheel travel which may be installed in the system, either by the manufacturer or by means of aftermarket or individually fabricated and installed components. While it is relatively straightforward to provide additional fender clearances, longer and/or taller springs, longer shock absorbers, etc., for increased suspension travel, this increased travel results in interference with the articulation of such solid axle and leaf spring suspension configurations. This is because as the axle articulates angularly and laterally relative to the vehicle chassis, e. g., with the left wheel raised and the right wheel lowered, the resulting angle of the axle produces an angular twist in the leaf spring assembly at each end of the axle.
These leaf spring assemblies are conventionally formed of a series of separate springs of different lengths, laminated together by a corresponding series of shackles or the like. As the distal ends of the spring are secured to the vehicle by lateral pivot bolts or pins, the distal ends maintain the angular orientation of the vehicle about their lateral pivot axes, while the center of the spring, which is bolted to the axle, is twisted to align with the lateral angle of the axle. It will be seen that this results in the twisting of the spring assembly, with resulting binding and resistance to spring travel and movement. It also places severe shear forces at the ends of the spring-to-chassis attachment bolts, leading to their early failure.
Accordingly, a need will be seen for a leaf spring to axle articulating connector which permits a solid axle to articulate angularly and laterally relative to the vehicle chassis, while simultaneously maintaining the linear alignment of the leaves of the leaf spring assembly at each end of the axle and their attachment points to the chassis. The present invention essentially comprises a longitudinally oriented pivot axis positioned between the center of the leaf spring assembly and its attachment to a solid or straight axle in a vehicle. The present invention thus allows full and complete angular movement of the axle relative to the longitudinal axis of the vehicle, while obviating any twisting forces in the leaf spring assembly. The present articulating connector may be used with front and rear wheel drive solid axle systems, with either overslung or underslung axle and spring assemblies.
A discussion of the related art of which the present inventor is aware, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 3,494,609 issued on Feb. 10, 1970 to Henry C. Harbers, Jr., titled xe2x80x9cLeaf Spring And Axle Seats,xe2x80x9d describes a series of clamps and shims for rigidly securing a leaf spring assembly to a solid axle housing, to preclude misalignment of the axle relative to the spring and vehicle (i. e., xe2x80x9ctoe-inxe2x80x9d and xe2x80x9ctoe-outxe2x80x9d). The Harbers, Jr. attachments teach away from the present invention, as they are expressly configured to prevent any relative movement between the axle and the spring assembly.
U.S. Pat. No. 3,591,163 issued on Jul. 6, 1971 to Richard D. Anderson, titled xe2x80x9cMounting,xe2x80x9d describes a plate for attaching a traction bar to a leaf spring suspension for a solid axle housing. The mounting holes for the plate are punched or stamped from the plate, to form a series of noncircular, tapered holes and corresponding scrap components. Each of these scrap components is further modified by removing a portion thereof, which when the components are reassembled with the plate, provide bolt passages therethrough. The stamped scrap components may be oriented in their holes in the plate as desired, thereby positioning the bolt holes as required for different U-bolt and spring dimensions, etc. As in the Harbers, Jr. assembly, the Anderson device teaches away from any movement between suspension components and axle, and is further directed only to longitudinal shifting of the axle, rather than angular movement relative to the vehicle""s horizontal axis.
U.S. Pat. No. 3,730,508 issued on May 1, 1973 to Daniel Marian et al., titled xe2x80x9cVariable Offset Spring Mounting Block For Load-Bearing Vehicles,xe2x80x9d describes an assembly comprising a pair of mating blocks, one of which secures to the axle and the other of which secures to the leaf spring attachment point. The two blocks include mating teeth, holes and pins, or other means for adjusting their mating fit, thereby adjusting the longitudinal position of the axle relative to the spring and vehicle. As in the other devices of the related art discussed above, the Marian et al. device is a rigid assembly when installed, and does not provide for any movement between the axle and spring.
U.S. Pat. No. 3,913,937 issued on Oct. 21, 1975 to William F. Longworth et al., titled xe2x80x9cUniversal Axle Pad And Clamp Assemblies For Vehicle Suspensions,xe2x80x9d describes an assembly for securing a solid axle and leaf spring assembly together. The assembly includes indicia for aligning the axle about its elongate axis, for adjusting the pinion angle of the axle. However, once the angle has been selected, the axle clamps are permanently and immovably welded to the axle, and the assembly is immovably bolted to the spring by means of a spring clamp and perch. Thus, the Longworth et al. assembly does not provide for any relative movement between the axle and its attachment to the leaf spring in any dimension whatsoever, whereas the present invention specifically provides for lateral articulation between the spring assembly and the axle to preclude binding of the spring assembly.
U.S. Pat. No. 4,227,716 issued on Oct. 14, 1980 to Sigurd A. M. Nordstrom, titled xe2x80x9cArrangement For Attaching Spring Assemblies To Vehicle Axle Housings,xe2x80x9d describes an assembly comprising an opposed pair of brackets which are welded to opposite sides of a solid axle housing. Lugs or ears extending from the brackets provide for the attachment of the bracket and axle assembly to a leaf spring assembly. The Nordstrom assembly is thus more closely related to the assembly of the Longworth et al. ""1937 U.S. Patent discussed above than to the present invention, due to the rigid, immovable mounting of the Nordstrom assembly and the lack of any provision for articulation between axle and spring, particularly angularly relative to the vehicle""s longitudinal axis.
U.S. Pat. No. 4,519,590 issued on May 28, 1995 to Wayne E. Wells, titled xe2x80x9cAxle Clamp For Filament Reinforced Synthetic Material Leaf Springs,xe2x80x9d describes a clamp assembly for positively securing such a leaf spring to an axle assembly. The Wells device specifically precludes any linear or angular movement of the axle relative to the spring, and thus is more closely related to the axle and spring securing means disclosed in the Harbers, Jr. ""232, Longworth et al. ""937, and Nordstrom ""716 U.S. Patents discussed further above, than to the present invention with its provision for angular movement of the axle relative to the attached leaf spring in an axis parallel to the longitudinal axis of the vehicle.
U.S. Pat. No. 4,553,774 issued on Nov. 19, 1985 to George D. Malcolm, titled xe2x80x9cVehicle Suspension,xe2x80x9d describes an assembly in which the leaf spring assembly is captured between a beam or solid axle and an adjacent but spaced apart stub axle. Wedges are driven between the stub axle and the spring, to hold the spring securely against a spacer plate. Malcolm notes that the advantage of this assembly is that the spring is positioned closer to the axle, thus reducing relative movement and bending moments between the two components. Thus, Malcolm teaches away from the present invention, with its means providing angular articulation between the axle and associated leaf spring, with the assembly of the Malcolm U.S. Patent being more closely related to the disclosures of the Harbers, Jr. ""232, Longworth et al. ""937, Nordstrom ""716, and Wells ""590 U.S. Patents discussed further above, than to the present invention.
U.S. Pat. No. 4,684,110 issued on Aug. 4, 1987 to Robert F. Sale et al., titled xe2x80x9cLeaf Spring Clamp With Attachment Means,xe2x80x9d describes an axle and leaf spring attachment assembly which is quite similar to that disclosed in the Wells ""590 U.S. Patent discussed further above, and which bears a much closer resemblance to the Wells ""590 device than to the present invention. (It is noted that Wells is shown as the second inventor in the Sale et al. Patent.) Accordingly, the points raised in the discussion of the Wells ""590 U.S. Patent regarding the differences and distinctions between the device of that patent and the present invention, are seen to apply here as well.
U.S. Pat. No. 4,801,129 issued on Jan. 31, 1989 to Wayne E. Wells, titled xe2x80x9cLeaf Spring Clamp With Attachment Means,xe2x80x9d describes yet another assembly more closely related to the devices disclosed in the ""590 U.S. Patent to the same inventor and to the ""110 U.S. Patent to Sales et al., discussed further above. The points raised in the discussion of those patents are accordingly seen to apply here as well, as none of these U.S. Patents provide for lateral articulation between the axle and leaf spring assembly to preclude lateral binding of the spring laminations, as provided by the present invention.
U.S. Pat. No. 5,634,656 issued on Jun. 3, 1997 to Raymond L. Banks, titled xe2x80x9cAxle Alignment Assembly,xe2x80x9d describes an alignment adjuster added to an otherwise conventional solid axle perch between the axle and leaf spring assembly. The adjuster causes the axle perch to pivot about its conventional pivot point extending from the uppermost spring, about a vertical axis. However, the Banks assembly otherwise immovably secures the axle to the spring assembly and does not allow angular articulation of the axle relative to the spring about an axis parallel to the vehicle""s longitudinal axis, as provided by the present assembly. It is also noted that the only movement allowed by the Banks device is during manual adjustment on a stationary vehicle, with the assembly being locked during vehicle motion. In contrast, the present device has no adjustment (other than perhaps conventional shims and the like), but permits fully automatic articulation of the axle relative to the spring during vehicle operation, unlike the Banks assembly.
Finally, U.S. Pat. No. 5,950,971 issued on Sep. 14, 1999 to Chris Koumbis et al., titled xe2x80x9cAssembly For And Method Of Mounting A Suspension Member To An Axle Housing,xe2x80x9d describes an assembly for attaching an axle to a suspension arm, rather than to a leaf spring assembly. A clamp assembly is welded in place around the suspension arm, with an attachment assembly welded to the axle. The two assemblies are bolted together by a lateral bolt, with shims placed adjustably between one end of the assemblies permitting adjustment of the pinion angle of the axle, i. e., the angle of the axle about its elongate axis. Accordingly, the Koumbis et al. assembly is more closely related to the assembly of the Longworth et al. ""937 U.S. Patent, discussed further above, than to the present invention.
None of the above inventions and patents, either singly or in combination, is seen to describe the instant invention as claimed
The present invention comprises an articulating connector for securing a solid, straight axle to a leaf spring assembly. The present connector includes a generally horizontal pivot axis normal to the elongate axis of the axle assembly, and generally parallel to the longitudinal axis of the vehicle. The present invention enables an axle to articulate angularly about an axis parallel to the longitudinal axis of the vehicle without laterally twisting the leaf spring to which it is attached, thereby precluding binding of the leaf spring and resistance to spring and axle travel. The result is greater freedom of articulation for the suspension assembly of a vehicle equipped with such a straight axle and leaf spring suspension system.
The present articulating connector may be applied to the rear drive axle system of vehicles equipped with such an axle and suspension system, and/or may be applied to a front axle assembly comprising the same type of axle and suspension system. The present articulating connector is particularly valuable to off road vehicle enthusiasts having vehicles with solid axle and leaf spring suspensions, who have occasion to take their vehicles over very rough and unimproved surfaces. The present articulating connector will also find great utility in military vehicles incorporating suspensions with which it is compatible, as well as vehicles used by contractors and others who may have occasion to take their vehicles off road and over relatively rough and unimproved terrain.
Accordingly, it is a principal object of the invention to provide an improved leaf spring to axle articulating connector, providing lateral angular articulation of a solid axle about an axis parallel to the longitudinal axis of the vehicle without applying lateral twisting forces to the leaf spring assembly to which the axle is attached, thereby increasing suspension articulation for the vehicle and obviating spring binding.
It is another object of the invention to provide an improved leaf spring to axle connector having a generally longitudinally oriented pivot axis disposed between the axle and the leaf spring assembly, providing lateral articulation of the axle relative to the spring.
It is a further object of the invention to provide an improved leaf spring to axle connector providing fixed alignment of the axle normal to the elongate axis of the spring assembly.
An additional object of the invention is to provide an improved leaf spring to axle connector including lubrication means therefor, and provision for installation with both underslung and overslung axles.
It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.